甘肃岷县永光村滑坡特征及其成因研究

doi:10.7522/j.issn.1000-0240.2019.0110

摘要/Abstract

摘要： 泥流型黄土滑坡发生的条件除一般滑坡具有的条件之外，还应包括特殊的状态因素、触发因素及相应的驱动剪应力条件。通过对甘肃岷县永光村滑坡的现场勘察和实地调查，分析其成因，结果表明：永光村滑坡平面形态虽与泥流类似，但其具有滑坡形成区以及滑坡发生所需要的特殊的地形地貌、岩土体性质以及水文地质条件。永光村滑坡发育于沟道上游的黄土塬地带，临空面较大，滑坡剪出口位置高，具有较高的势能，滑坡体的主要岩土体是马兰黄土，黄土具有大孔隙结构，垂直节理发育，有利于地表水的下渗。下部为新近系泥岩，渗透系数低，为一相对隔水层。长期灌溉导致地下水位较高，黄土层存在软弱夹层，地下水位上升，导致其软化饱和，强度迅速降低，形成潜在滑动面。永光村滑坡亦具有圆弧形的滑坡后壁，滑坡后缘顶部分布有多条拉张裂缝，在前期发生降雨的外部条件下，在岷县“7·22”地震诱发下，发生了低角度、快速和远程的泥流型黄土滑坡，滑体在冲出沟口后形成了扇形堆积区。永光村滑坡是一种特殊的地震引发的泥流型黄土滑坡。目前，泥流型黄土滑坡的研究还处在探索阶段，是作为黄土滑坡分类的一种补充，建议进一步加强对此类灾害发生机理及其稳定性计算方法的深入研究。

关键词: 泥流型黄土滑坡, 降雨, 地震, 成因, 液化

Abstract: In addition to the general conditions of landslides, the conditions for the occurrence of mud-flow loess landslides should include special state factors, triggering factors and corresponding driving shear stress conditions. Through on-site investigation and field investigation of Yongguangcun landslide in Minxian County, Gansu Province, the results show that although the plane shape of Yongguangcun landslide is similar to that of mud flow, it has the special landform, geomorphology, rock and soil properties and hydrogeological conditions needed for landslide formation and occurrence. Yongguangcun landslide develops in the Loess Plateau area upstream of the ditch. It has large free surface, high shear outlet position and high potential energy. Malan loess is the main rock and soil body of the landslide. Loess has large pore structure and vertical joint development, which is conducive to the infiltration of surface water. The lower part is Neogene mudstone with low permeability coefficient, which is a relative aquifer. Long-term irrigation results in higher groundwater level, weak interlayer in loess layer and rising groundwater level, which leads to softening and saturation, rapid reduction of strength and formation of potential sliding surface. Yongguangcun landslide also has an arc-shaped back wall of the landslide. There are many tension cracks on the top of the back edge of the landslide. In the absence of rainfall, under the external conditions of Minxian "7·22" earthquake, a low-angle, fast and long-distance mud-flow loess landslide occurred. The sliding body formed a fan-shaped accumulation area after it washed out of the ditch. Yongguangcun landslide is a special kind of mud-flow loess landslide caused by earthquake. At present, the research of mud-flow loess landslide is still in the exploratory stage, which is a supplement to the classification of Loess landslide. It is suggested that further study on the mechanism of such disasters and the calculation method of their stability should be strengthened.

Key words: mud-flow loess landslides, rainfall, earthquake, causes, liquefaction

中图分类号:

P642.2

王国亚, 任路滨, 吴玮江, 宿星, 冯乐涛, 姚正学. 甘肃岷县永光村滑坡特征及其成因研究[J]. 冰川冻土, 2019, 41(2): 392-399.

WANG Guoya, REN Lubin, WU Weijiang, SU Xing, FENG Letao, YAO Zhengxue. Characteristics and causes of the landslide outbreaking in Yongguangcun, Minxian County, Gansu Province[J]. Journal of Glaciology and Geocryology, 2019, 41(2): 392-399.

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